Astra 1B

Names	Satcom K3
Mission type	Communications
Operator	Société Européenne des Satellites / SES Astra
COSPAR ID	1991-015A
SATCAT no.	21139
Website	ses.com
Mission duration	12 years (planned) 15 years (achieved)
Spacecraft properties
Bus	GE-5000 (formerly AS-5000)
Manufacturer	GE Astro Space (formerly RCA Astro Electronics)
Launch mass	2,580 kg (5,690 lb)
Power	2,136 watts
Start of mission
Launch date	2 March 1991, 23:36:00 UTC
Rocket	Ariane 44 LP H10 (V42)
Launch site	Centre Spatial Guyanais, ELA-2
Contractor	Arianespace
Entered service	May 1991
End of mission
Disposal	Graveyard orbit
Deactivated	14 July 2006
Last contact	2002
Orbital parameters
Reference system	Geocentric orbit[1]
Regime	Geostationary orbit
Longitude	19.2° East
Transponders
Band	16 Ku-band
Bandwidth	26 MHz
Coverage area	Europe
Astra constellation ← Astra 1A Astra 1C →

Astra 1B was the second of the Astra communications satellites launched and operated by SES (Société Européenne des Satellites) to add extra capacity to the satellite television (direct broadcasting) services from 19.2° East, serving Germany, the United Kingdom and Ireland.

Satcom K3

SES bought the satellite in 1989 from failed direct broadcast satellite (DBS) company Crimson Satellite Associates while still under construction by GE Astro Space (as Satcom K3).^[2] Twelve years later, in 2001, SES acquired GE Americom, which originally was to operate the Satcom K3 satellite (and was itself the result of General Electric's purchase of RCA Corporation in 1986) and renamed it "SES Americom". It was merged with SES New Skies to form SES World Skies before the company was merged into its parent company, SES S.A. in 2011.

Mission

On 4 June 1991, Astra 1B suffered an attitude control failure, causing minor drift in north–south direction, meaning that it became difficult to obtain a steady lock on the satellite. This was most notable on analogue transmissions where the picture would move from clear to carrying sparklies and back again. The failure was likely caused by recent solar winds which impacted the electronics on both the primary and the backup momentum wheels. In September 1991, SES dealt with the failure by permanently deactivating the automatic control mode for the attitude subsystem.^[3]

Along with Astra 1C, Astra 1B was to be replaced in 2002 with Astra 1K, which failed to launch successfully, and as a result it continued to serve a longer life than expected, only falling from use when digital television on Astra 2A removed the majority of United Kingdom and Ireland targeted channels from 19.2° East.^{[citation needed]} From 2005, SES claimed that the satellite was in use for VSAT services, however no transponders were powered, and the satellite drifted to around 19.5° East. One transponder was reactivated in October 2005, but was carrying only colour bars.^{[citation needed]}

Decommissioning

On 16 June 2006, SES confirmed that Astra 1B would be decommissioned and de-orbited within weeks after Astra 1KR, the satellite which would replace Astra 1B and 1C, reached the operational orbital position of 19.2° East.^[4] It was officially end-of-lifed on 14 July 2006; close to four years after it had ceased carrying signals, ending SES's claims that the craft was operational.^{[citation needed]}

Transponders

Astra 1B transponders were used in the following ways during the operational life of the satellite:^{[citation needed]}